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this is a common area of confusion. people read a number and then draw conclusions, often inaccurately. i see so much dyno talk out there, it's silly, and most of it has no basis in reality. i've spent about 300 hours on various dynos, and have had the opportunity to learn a lot about what they are good at and good for, and what they are not.
porsche lists the S at 190 at the crank. that is with a brand new engine in perfect running order.
if your engine only made 139 at the wheels, then i would say it was probably not in perfect running order, because you should have made about 165. if i had to guess, i would say that engine had about 100k miles on it. you will lose about 1% of your power for every 10k miles on an engine.
also, different dynos read differently. a windyn will not read the same as a mustang, which will not read the same as a dynojet, none of which will read the same as a dynapak. the differences can be as much as 10%.
further, tire pressure, strap tension, air temp, humidity, yada yada, can all be factors which can alter the numbers.
that is why the only thing that matters is the before and after, and even then, only what is at the wheels. calculating forward to the crank is mathematical masturbation.
drivetrain loss can be measured though, on an eddy current dyno (unlike a standard dynojet 248). if you do measure it, you will find that it is between 30 and 40hp on a 944/968. once measured, you can then add that to your rwhp numbers and get a real crank number.
215 is no joke though. that's a significant increase for a normally aspirated engine. that's a 13% increase.
yes, bigger numbers can be reached, but again, at the expense of how it can be driven. you could probably get close to 300 hp out of that engine, but it would idle at 1500 and only have power up over 4k rpm. not exactly fun to drive back and forth to work. such an engine would also cost you a bundle. the last 944 engine i did like that was about $25k, and that was over 20 years ago.
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